Liquid laundry and dishwashing detergents play an essential role in the lives of consumers. Detergents are available in a variety of forms, such as the conventional detergents that are typically measured out by the consumer immediately before use (including those in concentrated form), as well the more recent unit dose detergent packets, where a pre-measured quantity of the detergent is encased in a water soluble film. Unit dose detergent packets generally contain less water than the other forms. This is driven by the fact that the typical water soluble films used for encasing the detergent, such as partially hydrolyzed polyvinyl alcohol homopolymers (PVOH), are sensitive to the presence of water, and can tolerate only a limited amount before premature dissolution.
In addition to cleaning performance, the aesthetic look and feel of a detergent is an important consideration for consumers. Thus, detergents typically contain a variety of ingredients that impact functionality, aesthetics, or both, including, for instance, surfactants, solvents, optional builder, and opacifiers.
Opacifiers are materials that make a liquid system opaque. Thus, opacifiers are used to modify the appearance or aesthetics of detergents, for instance, by transforming the liquid from clear or translucent to opaque. Opacifiers can provide a uniform, luxurious, “lotionized” appearance to a liquid product. Opacifiers are usually formed of submicron sized particles that are delivered to a formulation as a suspension of the particles in a solvent (typically water).
Since opacifiers are targeted to a formulation's aesthetics, it is generally desirable that their inclusion not interfere with the function of the formulation or otherwise negatively impact the formulation. For instance, opacifiers that exhibit limited compatibility with other materials in the formulation, have issues with stability, exhibit spotting or residue formation, are not favored. In addition, opacifiers that introduce large amounts of water into a formulation, e.g., by being effective only when used in large quantities, are also not favored, particularly for those formulations where limiting the quantity of water is desired, such as in concentrated detergents or unit dose packets.
It would be an advance in the art to develop new detergent composition opacifiers that exhibit improved properties over known materials, such as formulation stability and efficient opacifying characteristics at low use levels.